The invention relates to a replacement front wheel assembly for a roller board having a footboard provided at the rear end portion thereof with at least one wheel and at the front end portion thereof with a steering head bearing means for connection of a front wheel assembly and a steering rod connected to the front wheel assembly.
Roller boards most recently have become trendy sports equipment. They were introduced into the market in large numbers in a large variety of different kinds. There are basically different types of roller boards, including boards with one front wheel and boards with two front wheels. Roller boards having one front wheel are considerably less expensive to manufacture and thus correspondingly less expensive as regards the sales price thereof. Thus, they have stood up well in the market, and a very large portion of the roller boards sold so far can be reckoned among these xe2x80x9csingle-track roller boardsxe2x80x9d. In the overall construction thereof, these single-track roller boards are very similar to the long known children""s scooters. They are basically just of smaller built than the latter and in most cases provide the possibility of being brought into a handy shape for transport, by folding up components, sliding them together, etc.
Differing from these single-track roller boards are roller boards with two front wheels. These front wheels are individually joined to the footboard of the roller board by means of a steering mechanism and, by laterally pivoting the steering rod of the roller board, can be steered into a corner in synchronism, but each wheel being pivoted around its own pivot axis. During such pivoting of the steering or control rod for turning or cornering of the front wheels, there is typically caused tilting of the footboard at the same time, which automatically provides for the user to assume an inclined position as well. The advantage of such roller boards with two front wheels on the one hand resides in more stable handling ability and in particular also in more stable cornering ability. An additional advantage consists in that such roller boards can stand on their own, which of course is not possible with single-track roller boards. A significant disadvantage of such roller boards consists in that they are relatively complex in manufacture. Another handicap of such roller boards, that is due to the relative complex construction thereof as well, is that it has not been possible to produce a sufficient number of roller boards with two front wheels in the most recent boom period in which the demand for roller boards all over the world could not be fulfilled. This had the effect that they lost more and more market shares to single-track roller boards. The inventor of the present invention thus assumes that a retrofitting set allowing single-track roller boards to be relatively easily and inexpensively converted into such roller boards with two front wheels, could be very successful in the market.
It is thus the object of the present invention to make available a replacement front wheel assembly of the type indicated, by means of which single-track roller boards can be retrofitted relatively easily and inexpensively to such roller boards with two front wheels.
According to the invention, this object is met by a replacement front wheel assembly which is characterized in that the front wheel assembly comprises a connecting member for connection to the steering head bearing means as well as two front wheels that are each offset towards a respective side of the longitudinal axis of the roller board.
The steering head bearing means of a roller board typically has a construction similar to the steering head bearing of a bicycle, with two ball bearings, which are disposed at the upper and lower ends, respectively, of the tubular steering head, supporting a tubular connecting member on which corresponding bearing shells for the ball bearings are provided. The relative position of the bearing shells on the connecting member relative to each other may be changed, for example, via a screw thread. In this manner, the bearing clearance can easily be adjusted. In case of the single-track roller boards usual in the trade, the one front wheel is adapted to be rotated together with a corresponding connecting member in the steering head bearing means. The connecting member, at the top end thereof, has a steering rod or handlebar connected thereto, i.e. the latter is typically clamped thereto by means of a threaded connection. The steering motions of the steering rod are transferred to the front wheel directly, so that turning of the steering rod into the desired cornering direction has the effect that the front wheel is turned into this cornering direction as well. According to the present invention, the connecting member, instead of one single front wheel, is provided with two front wheels that are each arranged offset to a respective side of the longitudinal axis of the roller board. By relatively simple replacement of the xe2x80x9csingle-track front wheel assemblyxe2x80x9d with the xe2x80x9creplacement front wheel assemblyxe2x80x9d according to the invention, it is thus possible to convert a single-track roller board into a roller board with two front wheels. Preferably, the two front wheels are mounted on the front wheel assembly such that pivoting of the steering rod to one side of the longitudinal axis of the roller board effects cornering or turning of each individual wheel into this direction. It is particularly preferred if both wheels, though being turned individually about different steering axes, are turned in synchronism with each other so that both front wheels follow the proper curved path each.
Preferably, the two front wheels, alternatively or in addition, are mounted on the front wheel assembly such that, upon mounting of the replacement front wheel assembly on the roller board, turning of the steering rod effects turning of the two front wheels into the same direction to which the steering rod has been turned. A simple embodiment, in which turning of both wheels can be realized by turning of the steering rod only (whereas no turning of the wheels by tilting of the steering rod can be realized), comprises a transverse bar which is secured to the lower end of the connecting member and which has one front wheel each connected to the respective outer ends thereof. When the steering rod is turned, the transverse rod together with the two front wheels attached thereto is turned as well. By slight inclination of the axis of the steering rod, i.e. of the steering head bearing, it can be ensured that the roller board, despite this simple construction, upon cornering takes the required inclined position. However, particularly advantageous is the combination of the two steering mechanisms with each other, i.e. turning of each individual front wheel upon lateral pivoting of the steering rod and common rotation of the two wheels jointly about the steering axis. With this combination, extremely maneuverable roller boards can be produced. On the other hand, it is also possible to produce roller boards with very high track stability, for example, roller boards for high speeds with good straight-running properties which nevertheless have good steering properties.
Preferably, the front wheels are connected to the outer ends of a transverse bar, and it is particularly preferred to connect the transverse bar to the connecting member such that, upon mounting of the replacement front wheel assembly on the roller board, it is pivotable about the longitudinal axis of the roller board, but fixed about the vertical axis. This type of mounting can be carried out preferably by means of a U-shaped holding means on the connecting member, with the two legs of the xe2x80x9cUxe2x80x9d-shape being directed downwardly. It is thus possible to provide a pin in the longitudinal direction of the roller board between the two legs of the xe2x80x9cUxe2x80x9d-shape. The transverse bar may be pivotally supported on this pin. By means of this type of mounting, it is ensured at the same time that the transverse bar is connected to the connecting member in fixed manner about the vertical axis.
The transverse bar and the connecting member as well as all components of the replacement front wheel assembly in general are arranged relative to the roller board so as to be rotatable in the steering head bearing means. It is thus pointed out that, in the present application, all statements, for example, with respect to the direction or arrangement of individual components of the front wheel assembly or of the entire replacement front wheel assembly, made with reference e.g. to the longitudinal direction of the roller board, are to be understood as relating to the xe2x80x9cneutral settingxe2x80x9d of the roller board. This neutral setting of the roller board is understood to be the position of the roller board in which the same runs straight ahead.
Preferably, each of the front wheels is connected by means of an axle support to the transverse bar so as to be pivotable about the vertical axis and the front wheels are connected to each other so as to be pivotable in synchronism with each other only.
At least one of the two axle supports preferably is connected to the connecting member such that, when the replacement front wheel assembly is mounted to the roller board, pivoting of the steering rod around the longitudinal axis of the roller board effects turning of each individual one of the two front wheels. The connection of the at least one axle support on the connecting member is carried out, for example, by means of a connecting rod. The connecting rod may be connected at one end thereof to the axle support at a location that is offset from the vertical turning axis of the axle support a certain distance forwardly in running direction, and at the other end thereof may be connected to the connecting member at a location that is offset from the longitudinal turning axis of the transverse bar a certain distance upwardly towards the steering head bearing means. With this arrangement of the connecting rod, tilting of the steering rod about the longitudinal turning axis of the transverse bar results in shifting of the connecting rod and, accordingly, in turning of the axle support about the vertical turning axis of the axle support. Due to the synchronous connection of the two axle supports to each other, synchronous turning of both wheels in common manner upon pivoting of the steering rod is ensured. If the steering rod is rotated about its turning axis as well, turning of the wheels is effected in addition to the steering motion of the wheels by pivoting of the steering rod, so that an extremely narrow cornering radius is possible upon pivoting and turning the steering rod in the same direction.
As an alternative, the axle supports and preferably also the transverse bar are tilted towards the front in relation to the longitudinal axis of the roller board in such a manner that the vertical turning axis of the axle supports is also tilted towards the front in relation to the longitudinal axis of the roller board. If with this forwardly tilted vertical turning axis of the axle supports, the axles proper of the wheels are offset towards the rear with respect to the vertical turning axis, pivoting or tilting of the control rod towards the side effects turning of each one of the two front wheels. The connecting rod described in the preceding paragraph is not necessary with this construction. The synchronous connection of the two wheels to each other ensures synchronous pivoting of the two wheels.
Preferably, the replacement front wheel assembly is provided with a resetting means or mechanism tending to keep the front wheels in the neutral position. This resetting means provides for particularly stable straight-running properties, which is very desirable for reasons of driving safety. The stronger the resetting means, the more stable the straight-running properties and the less rapid the response of the steering system of the roller board to desired changes in direction. It is possible to provide two separate resetting means, on the one hand for resetting the rotation of the steering rod and on the other hand for resetting the pivoting of the steering rod. In particular in pivoting the steering rod, the resetting means can be constituted in that e.g. the vertical axis about which the axle support is pivotally supported on the transverse member, is slightly pivoted to the front or to the rear in running direction, so that the weight of the user of the roller board has the tendency of resetting the wheels to the neutral position during the ride. In addition to gravity, for example springs or other elastic members may be provided for the resetting means. For example, it is possible to provide two springs between the upper connecting web of the U-shaped holding means and the transverse bar such that one of the springs effects resetting upon pivoting of the control rod to the left and the other one of the springs effects resetting upon pivoting of the control rod to the right. Springs of flat resilient material or wound springs of spring wire may be provided for this purpose.
The latter may be supported e.g. on a bolt arranged above the transverse bar so as to extend through the two legs of the U-shaped holding means.
Preferably, there is provided a limiting means or mechanism for limiting the steering rotation of the control rod and the front wheels, respectively. This may be a fixed limiting means in the form of a stop. The U-shaped holding means may be designed such that, upon turning of the control rod, it abuts on the steering head bearing means or the footboard or any connecting member interposed there between, before one of the front wheels establishes contact with the footboard, for example. As an alternative, a kind of splashboard or covering may be provided for the wheels, which effectively prevents contacting between the front wheels and the footboard for example. It is also preferred to provide an adjustable limiting means that can be adjusted for front wheels of different sizes. It is thus possible to provide different limiting members for specific wheel sizes, which may be attached e.g. to the U-shaped holding means. In addition thereto, it is also possible to provide an adjustable limiting means which, for example, is provided with a graduation for indicating for each wheel size the proper position of the limiting means.
Preferably, there is provided a covering at least for the replacement front wheel assembly. It is particularly preferred to provide the transverse bar, the connecting member, the connecting rods and the axle supports with a covering completely or in part. The wheels also may be accommodated in part in the covering or may have a separate covering. The covering on the one hand has the advantage of reducing soiling of the components, in particular of the moving components. In addition thereto, the covering may also have a molding effect on the optical appearance of the replacement front wheel assembly and the roller board in its entirety, respectively. By way of different coverings, it is possible for example to give different designs to the replacement front wheel assemblies offered via different distribution channels. In addition thereto, the covering may be used as advertising carrier. For example, the coverings may be provided so as to be replaceable and may be mountable to the replacement front wheel assembly proper by means of simple pluggable and/or latchable connections.
In addition thereto, the invention relates to a roller board comprising a front wheel assembly according to the invention.
The invention moreover relates to a method of retrofitting a single-track roller board comprising a footboard which in the rear end portion thereof is provided with at least one wheel and in the front end portion of which there is mounted a front wheel in a steering head bearing means by means of a connecting member, so as to be rotatable by a steering rod, to a roller board comprising at least two steerable front wheels, said method comprising the steps of:
(a) demounting the steering rod from the connecting member;
(b) demounting the connecting member and one front wheel from the steering head bearing means;
(c) attaching a replacement front wheel assembly on the steering head bearing means; and
(d) mounting the steering rod on the connecting member of the replacement front wheel assembly.
It may be expedient to replace the bearings of the steering head bearing means during retrofitting of the roller board. As an alternative it is also possible, for example by omission of the bearings of the steering head bearing means and by simple threaded attachment of the connecting member to the steering head bearing means, to fixedly attach the connecting member to the remainder of the roller board. The steering head bearing thus is rendered inoperative and the replacement front wheel assembly is fixedly connected to the footboard. Steering of the roller board then is possible only by laterally pivoting of the steering rod. Retrofitting thus is rendered considerably less expensive on the one hand. On the other hand, it may also be expedient for other reasons if only one of the two steering mechanisms, namely the one operated by lateral pivoting of the steering rod, is available for steering the roller board.